(declare-const i0 Int)
(declare-const Str3 String)
(declare-const Str5 String)
(declare-const Str6 String)
(assert (= Str6 (str.++ Str5 Str3) (str.++ "" Str3 (str.++ Str6 (int.to.str i0)) Str5)))
(check-sat)
